Comment out unused signs_to_unix to silence compiler warning about forbidden zero-size array with -pedantic

src/formats/file_signature.cc

@@ -59,10 +59,11 @@ SignToMac signs_to_mac[] = {
 
 
 // File signature array.
+/*
 SignToUnix signs_to_unix[] = {
 
 };
-
+*/
 
 
 // Call Unix "file" command on a path.

src/formats/file_signature.h

@@ -57,8 +57,9 @@ struct SignToUnix {
 extern SignToMac signs_to_mac[];
 
 // File signature array.
+/*
 extern SignToUnix signs_to_unix[];
-
+*/
 
 
 // Get the MAC type (and creator) for a specific file.